Victoria Island is an island

Island

An island or isle is any piece of sub-continental land that is surrounded by water. Very small islands such as emergent land features on atolls can be called islets, cays or keys. An island in a river or lake may be called an eyot , or holm...

 in the Sacramento-San Joaquin River Delta in San Joaquin County, California

San Joaquin County, California

San Joaquin County is a county located in Central Valley of the U.S. state of California, just east of the San Francisco Bay Area. As of the 2010 census, the population was 685,306. The county seat is Stockton.-History:...

, twenty kilometres southwest of Stockton

Stockton, California

Stockton, California, the seat of San Joaquin County, is the fourth-largest city in the Central Valley of the U.S. state of California. With a population of 291,707 at the 2010 census, Stockton ranks as this state's 13th largest city...

. The 7200 acre (2,913.7 ha) island is bounded on the north by North Victoria Canal, on the northeast by Middle River, on the southeast by Victoria Canal, and on the south- and southwest Old River.

Buried impact structure

Oil exploration led to the discovery of a possible buried impact structure

Impact structure

The term impact structure is closely related to the terms impact crater or meteorite impact crater, and is used in cases where erosion or burial have destroyed or masked the original topographic feature with which we normally associate the term crater...

 in the sediments under the island. It was named the Victoria Island Structure

Victoria Island structure

The Victoria Island structure is a 5.5 km bowl-shaped structure buried in the shale sediments of the Sacramento-San Joaquin River Delta, west of Stockton, California...

after the island.